Students who took the drug reported side effects such as “needing to go to the loo more” and “inability to sleep” while “reduced appetite” was the most common.

Of those who admit taking it, 20% of the students say they swallow the pill on a daily basis.

Kingston University prof Andrea Petroczi worries that people might think it makes them cleverer. “It’s not a magic pill” she says, “it doesn’t work without putting the work in. It helps you to put more work in.”

Buying prescription drugs isn’t a crime in the UK, but supplying them is. This is currently being reviewed by the Advisory Council on the Misuse of Drugs.

Tab Editor-in-chief Jack Rivlin said: “Obviously there is a self-selection bias – people who take modafinil are much more likely to answer the survey – but it still shows massive growth for a drug most students hadn’t heard of three years ago.

“Modafinil is not a wonder drug – it doesn’t make you reach a higher limit of achievement than people who haven’t taken it. But it can massive improve your efficiency, so it’s a big boost to lazy people to force themselves to work.

“I don’t think anyone ever became cleverer because of modafinil, but it has allowed people to live up to their ability.”